<template>
  <div ref="dragDiv" class="drag">
    <div class="drag_bg"></div>
    <div class="drag_text">{{ confirmWords }}</div>
    <div ref="moveDiv" :class="{'handler_ok_bg':confirmSuccess}" class="handler handler_bg" style="position: absolute;top: 0px;left: 0px;" @mousedown="mouseDownFn($event)"></div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      beginClientX: 0, /* 距离屏幕左端距离*/
      mouseMoveState: false, /* 触发拖动状态  判断*/
      maxWidth: '', /* 拖动最大宽度，依据滑块宽度算出来的*/
      confirmWords: '向右拖动滑块验证', /* 滑块文字*/
      confirmSuccess: false /* 验证成功判断*/
    }
  },
  mounted() {
    this.maxWidth = this.$refs.dragDiv.clientWidth - this.$refs.moveDiv.clientWidth;
    document.getElementsByTagName('html')[0].addEventListener('mousemove', this.mouseMoveFn);
    document.getElementsByTagName('html')[0].addEventListener('mouseup', this.moseUpFn)
  },
  methods: {
    // mousedown 事件
    mouseDownFn: function (e) {
      if (!this.confirmSuccess) {
        e.preventDefault && e.preventDefault(); // 阻止文字选中等 浏览器默认事件
        this.mouseMoveState = true;
        this.beginClientX = e.clientX;
      }
    },
    // 验证成功函数
    successFunction() {
      this.confirmSuccess = true;
      this.confirmWords = '验证通过';
      if (window.addEventListener) {
        document.getElementsByTagName('html')[0].removeEventListener('mousemove', this.mouseMoveFn);
        document.getElementsByTagName('html')[0].removeEventListener('mouseup', this.moseUpFn);
      } else {
        document.getElementsByTagName('html')[0].removeEventListener('mouseup', () => {});
      }
      document.getElementsByClassName('drag_text')[0].style.color = '#fff';
      document.getElementsByClassName('handler')[0].style.left = this.maxWidth + 'px';
      document.getElementsByClassName('drag_bg')[0].style.width = this.maxWidth + 'px';
    },
    // mousemove事件
    mouseMoveFn(e) {
      if (this.mouseMoveState) {
        let width = e.clientX - this.beginClientX;
        if (width > 0 && width <= this.maxWidth) {
          document.getElementsByClassName('handler')[0].style.left = width + 'px';
          document.getElementsByClassName('drag_bg')[0].style.width = width + 'px';
        } else if (width > this.maxWidth) {
          this.successFunction();
        }
      }
    },
    // mouseup事件
    moseUpFn(e) {
      this.mouseMoveState = false;
      var width = e.clientX - this.beginClientX;
      if (width < this.maxWidth) {
        document.getElementsByClassName('handler')[0].style.left = 0 + 'px';
        document.getElementsByClassName('drag_bg')[0].style.width = 0 + 'px';
      }
    }
  }
}
</script>
<style scoped>
  .drag{
      position: relative;
      background-color: #e8e8e8;
      width: 100%;
      height: 40px;
      line-height: 40px;
      text-align: center;
      border: 1px solid #ccc;
      border-radius: 4px;
  }
  .handler{
      width: 40px;
      height: 38px;
      border: 1px solid #ccc;
      border-radius: 4px;
      cursor: move;
  }
  .handler_bg{
      background: #fff url("") no-repeat center;
  }
  .handler_ok_bg{
      border-top-left-radius: 0;
      border-bottom-left-radius: 0;
      background: #fff url("") no-repeat center;
  }
  .drag_bg{
      background-color: #7ac23c;
      height: 38px;
      width: 0px;
      border-radius: 4px 0 0 4px;
  }
  .drag_text{
      position: absolute;
      top: 0px;
      width: 100%;text-align: center;
      -moz-user-select: none;
      -webkit-user-select: none;
      user-select: none;
      -o-user-select:none;
      -ms-user-select:none;
  }
</style>
